Echocardiography, or Echo, is a noninvasive procedure used to assess the heart's function and structures. A transducer (like a microphone) sends out ultrasonic sound waves at a frequency too high to be heard. When the transducer is placed on your chest at certain locations and angles, the ultrasonic sound waves move through the skin and other body tissues to the heart tissues, where the waves echo off of the heart structures. The transducer picks up the reflected waves and sends them to a computer. The computer interprets the echoes as an image of the heart walls and valves, which is displayed on a screen.

An exercise echocardiogram may be performed in the physician's office, a clinic, or in the hospital. After the resting echo images have been obtained, you will begin to exercise on a treadmill or stationary bicycle. The physician will compare the resting echo with the echo done immediately after exercise.

An exercise echocardiogram can utilize one or more of four special types of echocardiography, as listed below:

• M-Mode echocardiography
  This, the simplest type of echocardiography, produces an image that shows movement of the heart structures rather than an actual picture of the heart. M-mode echo is useful for measuring heart structures, such as the heart's pumping chambers, the size of the heart itself, and the thickness of the heart walls.
  
  
• Doppler echocardiography
  This Doppler technique is used to measure and assess the flow of blood through the heart's chambers and valves. Doppler can detect abnormal blood flow within the heart, which can indicate a problem with one or more of the heart's four valves, or with the heart's walls.
  
  
• Color Doppler
  Color Doppler is an enhanced form of Doppler echocardiography. With color Doppler, different colors are used to designate the speed and direction of blood flow. This is a good technique for seeing leaky heart valves.
  
  
• 2-D (2-dimensional) echocardiography
  This technique is used to "see" the actual structures and function of the heart. The black and white pictures look like a heart in motion "cut open" for viewing. This enables the physician to see the various heart structures at work and evaluate them.
  

Reasons for the Exercise Echocardiogram

At Beaumont, an exercise echocardiogram, is usually performed after you have exercised on a treadmill. Sometimes, a stationary bicycle may be used to exercise. An Exercise echo may be performed for the following reasons:

• To determine limits for safe exercise in patients who are entering a cardiac rehabilitation program, such as after a heart attack or heart surgery
• To assess leg pain with exercise (also called intermittent claudication) in patients with suspected occlusion in the legs' circulatory system
• To evaluate blood pressure or heart beat during exercise
• To evaluate the cardiac status of a patient about to undergo surgery
• To determine the presence and extent of "blocked arteries".

Purpose

Same as for exercise stress test, and also to evaluate the heart muscle and valves in action.

How it works

The heart is evaluated with ultrasound, usually after administering a drug (dobutamine) that mimics the effects of exercise. Less frequently, it is done after an exercise stress test.

Preparation

Same as for an exercise stress test and echocardiography.

Test procedure

Same as for an exercise stress test, plus the following:

• An echocardiogram (see page 103) is taken before and after exercise.
• The test may also be performed with a medication, given through an intravenous tube, that mimics the effects of exercise and can therefore substitute for the exercise portion of the test (dobutamine). This is valuable in patients who cannot exercise.

After the test

• Same as for an exercise stress test.
• Factors affecting results
• Same as for echocardiography and an exercise stress test.
• Interpretation

The test is evaluated for the development of abnormal contractions (heartbeats) during exercise. This suggests an inadequate blood supply to the heart muscle.

Advantages

Same as for an exercise stress test, and also it's a noninvasive way to evaluate function of the heart muscle and valves and detect coronary disease.

Disadvantages

Same as for an exercise stress test, and also the equipment is expensive and not available at all testing centers.